1. Field of the Invention
This invention pertains to wheelchairs, related devices, and methods for use, particularly for transportation.
2. Description of Related Art
For individuals with partial or complete impairment of motor function as a result of spinal cord injury, spina bifida, multiple sclerosis, amyotrophic lateral sclerosis, or stroke, the wheelchair is commonly an essential means of daily mobility. Two important challenges are faced by the wheelchair user in order to successfully get around in his or her environment: The act of getting oneself into the wheelchair, also termed “transferring,” and the safe negotiation of indoor and outdoor surfaces alike. The act of transferring one's body into or out of a wheelchair presents a situation that often involves physical strain and awkward positioning of the arms, hands, feet, legs and torso; for many users who might wish to transfer into or out of a wheelchair with respect to a variety of different surfaces, this can severely limit the scope of physical activity. Experienced wheelchair users may wish to transfer to or from a wheelchair with respect to the ground, such as the grass at a park or a sandy beach, and this can be especially difficult even with the assistance of another person. The means of enjoying these locations is further precluded by the insufficiency of most wheelchairs to traverse these types of surfaces with safety and ease. There is a need for wheelchairs offering improved ease of transfer and which are suitable for traversing the broad range of surfaces encountered in the outdoors.
A wide variety of wheelchair designs are known, including wheelchairs with a single forward wheel such as three-wheel wheelchairs with relatively large forward wheels. Such wheelchairs can offer advantages in traversing rugged terrain, but present barriers to transferring due to the support structures holding the forward wheel in place. There is a need for rugged all-terrain wheelchairs whose support structures are minimally obstructive, thereby offering improved transferring into and out of the wheelchair.
Conventional wheelchairs, sometimes referred to as “cantilever” style wheelchairs, have relatively small forward wheels typically positioned laterally and rearward relative to the leading edge of the footrest of the wheelchair. This type of wheelchair offers the best scenario in terms of access for transferring and it may be suitable for smooth flooring and pavement but is generally unsuitable for rugged terrain. Previous attempts to make conventional wheelchairs useful on rugged terrain suffer from a variety of design challenges which can limit stability and reduce safety on very rough ground, and which may limit the overall maneuverability of the wheelchair. For users requiring stable performance on rugged terrain, there is a need for an improved wheelchair configuration.
There is a need for wheelchairs that are sufficiently robust for performance on rugged outdoor terrain yet are also lightweight, highly maneuverable and reasonably compact to allow the user to successfully negotiate tighter spaces indoors such as doorways, bathroom facilities, garages and elevators.
Even on presumably safe surfaces such as sidewalks, wheelchair users learn that they must be constantly vigilant about the upcoming surfaces since bumps, small objects, or other obstacles can cause a moving wheelchair to tip or cause the user to be propelled out of the wheelchair. There is a need for more robust wheelchairs that can remain stable and safe in spite of unevenness in the surfaces over which the wheelchair user must traverse.
Improved wheelchair designs and methods have been devised which may address one or more of these aforementioned weaknesses or other weaknesses in the prior art. Such weaknesses, however, are mentioned here only for illustrative background purposes. The embodiments hereafter described, while typically addressing one or more weaknesses in the prior art, need not directly or indirectly address all or any of the aforementioned weaknesses in the prior art to be within the scope of the various embodiments hereafter claimed. Further, any advantages stated or apparently inherent to any of the embodiments described hereafter are not intended as limitations that must necessarily be found in any or all aspects of the invention.